Lens protection for medical purposes

ABSTRACT

A low profile medical lens protector ( 100 ) for a medical viewing device having a given diameter, comprising: a rotatable view-through element; a motor which rotates said view-through element; and a housing ( 140 ) enclosing said view-through element and said motor, characterized in that said housing has an outer diameter less than 10 mm greater than said given diameter.

RELATED APPLICATIONS

This application is a U.S. national filing of PCT Application No.PCT/IL01/00158, filed on Feb. 20, 2001. This application is also relatedto PCT Application No. PCT/IL00/00750, filed on Nov. 15, 2000, thedisclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention is related to the field of protection of viewingdevices from interference, especially by means of centrifugal lensprotectors.

BACKGROUND OF THE INVENTION

Various optical systems are required to operate in adverse environments,in which various solid particles and/or fluid droplets etc. and/or otheragglomerations of one or more materials of various stickiness orviscosity (herebelow collectively termed “debris”) may adhere to thelens and reduce image quality.

One solution is a centrifugal lens protector, in which a spinning glassdisc is placed before the lens, so that all the particles areintercepted by the disc. The centrifugal force generated by the disc asit rotates throws the particles towards the circumference of the disc,where they fall off and/or otherwise stop interfering with the image.

U.S. Pat. No. 5,223,880 to Rapp, the disclosure of which is incorporatedherein by reference, describes a camera protector in which the disc isintegrated with a rotor of a magnetic motor, with a casing surroundingthe disc being the motor housing.

U.S. Pat. No. 5,315,333 to Nash, the disclosure of which is incorporatedherein by reference, provides a single motor coupled to the disc using aband. The disc is mounted on two lines of bearings. The lens protectiondevice is mounted on the camera, to isolate lens from gyroscopic andvibration forces.

Australian application 9515074, the disclosure of which is incorporatedherein by reference, describes another band-based system, in which thedisc is said to rotate at between 2600 and 3000 RPM. It is suggested touse a curved or hydrophobic surface to assist in water removal. Themotor can be powered using the camera battery pack or using a separatebattery.

A particularly difficult environment to view is the inside of the humanbody. Various medical instruments have been devised for this purpose,for example: the endoscope, the laparoscope which is used for treatment,for example surgery or cauterization or alternative methods oftreatment. Commonly an endoscope lens becomes at least partiallyoccluded by body fluids and particles, becoming inoperative. In suchcircumstance the lens must cleaned. One method of cleaning the lens isto stream a jet of water at the lens, the stream coming from a tubewhich generally is an integral part of the endoscope assembly. Sometimesthe endoscope must be withdrawn for cleaning and reinserted, atime-consuming, risk-increasing and often uncomfortable procedure.

SUMMARY OF THE INVENTION

An aspect of some embodiments of the present invention relates to acentrifugal lens protector, for medical viewing devices. In an exemplaryembodiment of the invention, the protector comprises a transparentview-through element, which is fixed to a part of a motor. Optionally,the motor is co-axial with the view-through element. In an exemplaryembodiment of the invention, the motor is an electric motor, optionallybrushless, and the view-through element is integral with the rotor ofthe motor, e.g., having a plurality of magnets fixed thereon. Possibly,a housing of the protector forms the stator. In an exemplary embodimentof the invention, the housing is used to couple the protector to theviewing device or is integral with the viewing device. In an alternativeembodiment, the motor is an electrostatic motor, with the magnets beingreplaced by electrostaticly charged elements.

In an exemplary embodiment of the invention, the magnets extend axiallyfor a considerable distance away from the view-through element, possiblybeing contained in a cylinder defined by the view-through element, orextending out radially by a small amount. In an exemplary embodiment ofthe invention, the motor defined by the magnets is hollow, to receivethe tip of the viewing device. Alternatively, neither the magnets northe coils enclose the viewing device. Optionally, the poles of themagnets are axially oriented.

In an exemplary embodiment of the invention, the lens protection elementdoes not significantly add to the diameter of an entrance aperture ofthe viewing device, while not substantially blocking viewing ability ofthe device, for example, by being axially disposed relative to theviewing device. For example, the diameter of the aperture may remain thesame, or be increased by less than 50%, less than 40%, less than 30% oreven less than 10%. For example, the outer diameter may be increased byless than 5 mm, less than 3 mm, less than 2 mm or less than 1 mm. In anexemplary embodiment of the invention, the housing diameter and/orsheath diameter are selected to match standard endoscope conveying tubediameters.

Exemplary medical viewing devices include invasive medical devices, suchas viewing or tool carrying endoscopes, laparoscopes and catheters,which devices may be flexible or rigid and non-invasive devices, such assurgical microscopes and magnifying goggles or glasses attachments.

The view through element may be optically inactive, e.g., being atransparent disc, flat or convex, or active, for example, being a lens(e.g., instead of or in addition to a lens of the viewing device) or afilter.

In an exemplary embodiment of the invention, the lens protector isprovided integral with the viewing device, for example, being encased ina same tube as the viewing device and/or replacing the outermost opticalelement of the viewing device. Alternatively, the lens protector isprovided as an add-on. The add-on may be merely attached to the end ofthe viewing device, optionally, with control wires leading to the otherend of the device. Alternatively, the add-on may comprise a sheath thatencases the viewing device. The sheath optionally includes one or morechannels, for example, for providing lens cleaning fluid, one or morelight sources, vacuum and/or tools. Optionally, the channels areelastically compressible towards the viewing device, when not in use.Alternatively or additionally, the lens protector includes at least oneaperture for alignment with at least one tool-channel of the viewingdevice.

An aspect of some embodiments of the present invention relates to acontact-sensitive lens protector. In an exemplary embodiment of theinvention, the view-through element stops rotating when it contacts asurface, for example a membrane in the body, for example, to preventinadvertent damage to body tissues. In an exemplary embodiment of theinvention, the lens protector is provided with enough power to generatea torque that can sustain substantially free rotation, but not withenough power to re-start the rotation once it has stopped. In anexemplary embodiment of the invention, a control box includes arestart-button, for sending a power surge to the lens protector, so thatit can be restarted.

In an exemplary embodiment of the invention, the lens protector ispacked with a power supply (e.g. a battery) that once turned on, canoperate only for a limited amount of time, for example, between 5minutes and two hours. After that time, the power supply runs out andcannot be replaced without damaging the lens protector.

There is thus provided in accordance with an exemplary embodiment of theinvention, a low profile medical lens protector for a medical viewingdevice with an entrance aperture having a given diameter, comprising:

a rotatable view-through element which does not block said entranceaperture;

a motor which rotates said view-through element; and

a housing enclosing said view-through element and said motor,characterized in that said housing has an outer diameter less than 10 mmgreater than said given diameter. Optionally, said outer diameter isless than 5 mm greater than said given diameter. Optionally, said outerdiameter is less than 2.1 mm greater than said given diameter.

In an exemplary embodiment of the invention, said view-through elementis integral with a rotor of said motor. Alternatively or additionally,said housing is integral with a stator of said motor. Alternatively oradditionally, said housing has a flared rim.

In an exemplary embodiment of the invention, said motor is a magneticmotor. Optionally, said motor comprises a plurality of axially disposedmagnets, attached to said view-through element. Optionally, theprotector comprises at least one tension ring preventing radial motionof said magnets. Optionally, said motor comprises a magnetic ring,attached to said view-through element.

In an exemplary embodiment of the invention, said motor comprises ahollow rotor. Optionally, the protector comprises at least two axiallydisplaced bearings coupling said rotor to said housing. Optionally, saidat least one of said bearings is a slip ring bearing. Optionally, saidat least one of said bearings is rotating bearing. Alternatively oradditionally, said bearings are at either end of said housing.

In an exemplary embodiment of the invention, the protector comprises apower source that provides only enough power to said motor to maintainsaid view-through element in rotation and not to initiate rotation.Optionally, said power source is operative to provide a power surgesufficient to initiate rotation of said view-through element.

In an exemplary embodiment of the invention, said viewing devicecomprises an invasive viewing tube device. Optionally, said viewing tubeis flexible. Alternatively or additionally, said protector is adapted toattach to said viewing tube. Optionally, said protector is attached tosaid tube substantially only at a proximal part of said protector,distal from said view-through element. Alternatively, the protectorcomprises a sheath adapted to fit on said viewing tube. Optionally, saidsheath defines at least one axial tube.

In an exemplary embodiment of the invention, the protector comprises ashort sleeve for coupling said protector to said viewing tube.

In an exemplary embodiment of the invention, said protector is integralwith said viewing tube.

In an exemplary embodiment of the invention, said viewing tube comprisesat least one work channel and wherein said protector comprises at leastone tube extension that can be aligned with said channel.

In an exemplary embodiment of the invention, said view-through elementrotates at at least 5,000 r.p.m. Alternatively or additionally, saidview-through element rotates at at least 10,000 r.p.m. Alternatively oradditionally, said view-through element rotates at at least 20,000r.p.m.

In an exemplary embodiment of the invention, said protector has an outerdiameter of less than 30 mm. Alternatively or additionally, saidprotector has an outer diameter of less than 20 mm. Alternatively oradditionally, said protector has an outer diameter of less than 7 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the invention will be described withreference to the following description of exemplary embodiments, inconjunction with the figures. The figures are generally not shown toscale and any measurements are only meant to be exemplary and notnecessarily limiting. In the figures, identical structures, elements orparts which appear in more than one figure are preferably labeled with asame or similar number in all the figures in which they appear.Dimensions of components and features shown in the figures are chosenfor convenience and clarity of presentation and are not necessarilyshown to scale.

FIG. 1 is a schematic view of a lens protector with a sheath enclosingan endoscope, in accordance with some embodiments of the presentinvention;

FIG. 2 is a schematic enlarged view of a lens protector in accordancewith some embodiments of the present invention;

FIG. 3 is a schematic view of a section through a disc-rotor, two of itsmagnets and its housing-stator, in accordance with some embodiments ofthe present invention;

FIG. 4 is a schematic view of the moving part of a one-moving-part lensprotector, in accordance with an exemplary embodiment of the presentinvention;

FIG. 5 is a schematic oblique cross-sectional view of a housing for aone-moving piece lens protector in accordance with an exemplaryembodiment of the present invention; and

FIG. 6 is a schematic oblique cut-away view of a sheath of a lensprotector in accordance with an exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

FIG. 1 is a oblique schematic view of the inserted end of an endoscope90, with its head covered by a centrifugal lens protector 100, inaccordance with some embodiments of the present invention. (The distancebetween lens protector 100 and the head of endoscope 90 is exaggeratedfor clarity.)

At the front of endoscope 90 is a lens 92, held in a housing 96.Optionally one or more tubes 98 pass through housing 96. Tubes 98 may beused for a variety of functions, for example, for pumping gas into thevolume to be viewed, to suck fluids and particles out from the volume,to spray water for example to clean an area to be viewed or to cleanendoscope lens 92, to provide light, to provide therapeutic materialsand/or to provide tools. The sizes and number of tubes 98 may varybetween endoscopes. Different lens protectors may be provided fordifferent sized and configured endoscopes.

Lens protector 100 is affixed at the front of endoscope 90. A disc 102(or a curved plate or a lens or a filter) covers endoscope lens 92, andoptional tube extensions 170 cover the endings of tubes 98, continuingthe tube through lens protector housing 140.

In an exemplary embodiment of the invention, protector 100 comprises ashort sleeve (not shown) that mounts on the end of endoscope 90, forexample, using pressure (e.g., being elastic or including a tensionband) or an adhesive. Optionally, the short sleeve includes a tearstring for fast removal from the endoscope. Alternatively, protector 100includes one or more extensions (not shown) that fit into endoscopetubes. Alternatively, for some types of endoscopes, protector 100 fitson existing mounting locations of the inserted end of the endoscope.

In one embodiment, protector 100 fits to the end of endoscope 90.Alternatively, endoscope 90 (or another type of viewing element) isprovided through a larger tube and protector 100 is fixed to that tube.Wires for the protector may be provided through the outer tube.Alternatively, the protector is attached to the viewing device itself,even if the device is provided through an outer tube.

In an exemplary embodiment of the invention, a motor portion ofprotector 100, that rotates disc 102, extends between 2 mm and 20 mm,for example, 7.5 mm or 15 mm. For example, the length of the motorportion may be comparable to the diameter of endoscope 90 or even begreater. The short sleeve may be, for example, between 2 and 30 mm long,for example, 10 mm or 20 mm. Alternatively, an inner compression ring isprovided inside protector 100, to engage the endoscope. The disc isoptionally thin, for example, less than 1 mm or less than 0.5 mm.

In an alternative embodiment of the invention, protector 100 comprises asheath 190 that encloses endoscope 90. Sheath 190 may be integral withprotector 100 or it may by attached to the protector after manufacture,for example, being fit over the protector when mounting the protector onthe endoscope. An optional control box 104 controls the activities oflens protector 100 via one or more leads 132 that extend from lensprotector 100 to lens protector control box 104. As noted above, leads132 may pass through endoscope 90. Alternatively, leads 132 are embeddedin the sheath or lie between the sheath and endoscope 90. Box 104optionally includes a band or an adhesive backing for attachment to ahandle (not shown) of endoscope 90.

Optionally, sheath 190 is sealed to housing 140 in a water-tight seal,which may reduce the risk of contamination and the need for sterilizingof the endoscope itself (e.g., with the sheath being sterile anddisposable). Optionally, sheath 190 comprises a plurality of rings, tobetter seal the endoscope against an outer conveying tube, e.g., forapplications where the endoscope is in a pressurized environment. Sheath190 optionally includes one or more tubes, for example, for controlelements, suction and pressure for lens protector 100. In an exemplaryembodiment of the invention, sheath 190 comprise a fixed plate betweenendoscope 90 and disc 102, to prevent contaminants from reaching theendoscope through the disc area. A plurality of valve-openings areoptionally defined in the disc, for example, for passing tubestherethrough.

FIG. 2 is an oblique schematic view of centrifugal lens protector 100,in accordance with some embodiments of the present invention. Asubstantially transparent disc 102 is provided, which is held in housing140 in such a way as to enable disc 102 to rotate freely, as described,for example, below. Housing 140 attaches to the inserted end ofendoscope 90.

Housing 140 is optionally provided with a plurality of extensions 170,which are a continuation of tubing 98. Some passageways may be used forsuction, to remove fluids or particles from the environment of disc 102.In some embodiments of the invention, housing 140 is provided withdepressions or cavities 180 which act as receptacles or attachmentpoints for instruments. In some embodiments some cavities 180 may belocated inside extensions 170. One or more of extensions 170 may be usedfor control wires connecting to instruments outside the endoscope, forexample instruments held in cavities 180. Optionally, some passagewaysare used for more than one function.

FIG. 3 is a cut-through illustration of FIG. 2. Disc 102 is providedwith a plurality of axially aligned magnets 110. One end of each magnetis affixed to disc 102, for example using an adhesive or using a tensionring surround the magnets. Optionally, the magnets are mounted directlyon disc 102, for example, being held in depressions formed in disc 102.Magnets 110 extend axially from disc 102 into the volume of housing 140.Disc 102 is optionally held in place by a plurality of ball or cylinderbearings 150, which enable rotation. In some embodiments the diameter ofa bearing 150 is 0.2 millimeter. Alternatively or additionally, aslip-ring bearing is used. At the base of protector 100, a secondbearing 160 is optionally provided, for example, a slip-ring bearing.

In an exemplary embodiment of the invention, magnets 110 areinterconnected by a pair of optional sliding rings 112 and 114 whichserve, as tension rings, to prevent the centrifugal force of rotationfrom detecting the magnets from disc 102 or causing undue distortion.Sliding rings 112 and 114 slide in contact with bearings 160 and 150. Insome embodiments of the invention, the life time of protector 100 isrelatively short, so wear of the bearings is not crucial. Such sliprings may be mounted on the moving part (e.g. the disc) or on the staticpart (e.g., housing 140).

In an exemplary embodiment of the invention, the bearings are loose andserver merely to assists the initiation of rotation of disc 102. Afterthe initiation, air currents may prevent disc 102 from contactinghousing.

Optionally, magnets 110 and/or the inner surface of disc 102 includebearings or a smooth surface (e.g., with or without a coating), forsmoothing contact between the outside of endoscope 90 and the innersurface of protector 100.

A plurality of coils 130 are provided within the body of housing 140, ator close to the inner surface of housing 140. In some embodiments of theinvention, coils 130 are fabricated by a process of depositingelectroconductive material, e.g. copper or silver or platinum or anelectroconductive plastic in an especially formed cavity in housing 140.Many different lithographic methods may be used for fabricating coils130. Alternatively, the coils are deposited on a rigid or flexiblesubstrate and the substrate is inserted in housing 140.

Alternatively or additionally, coils 130 are wound on cores, optionallyferromagnetic cores. Coils 130, on their cores, are inserted into areceptive depression in housing 140. In some embodiments housing 140and/or coils 130 and/or the said cores are provided with means ofsecuring coils 130 in position in housing 140, for example, adhesives.In an exemplary embodiment of the invention, the positioning of thecoils is selected so that extensions 170 can pass between coils, forexample, a specific arrangement of coil locations for each endoscopedesign.

In an exemplary embodiment of the invention, the coils are wound onhousing 140 in a three phase air coil skew coreless coil, in which eachwinding encircles the housing, with its axial position varying from oneaxial end of the housing to the other and back, during a circuit. In anexemplary embodiment of the invention, the wire used is between 0.05 mmand 0.12 mm and the length of wire for each phase is about 3.2 m. Thefinal thickness of the windings is, for example, 0.2 mm.

Current supply to coils 130 is controlled by lens protector control unit104, which optionally comprises an electronic brushless commutator (notshown), for example a Philips TDA1540AT. A plurality of leads 132, whichin some embodiments may at least partially be comprised of wires, leadfrom control box 104 to coils 130. Changes of electric current in coils130 generate varying magnetic fields which act on magnets 110, causingdisc 102 to rotate, as well known in the art of magnetic motors. Invarious embodiments of the present invention the steady rate of rotationof lens protector 100 lies between 2000 r.p.m. and 40,000 r.p.m, forexample, more than 5,000 r.p.m. or more than 20,000 r.p.m., or anysuitable intermediate speed.

To illustrate an exemplary embodiment of the present invention, FIG. 3shows diametrically opposite magnets and coils, at an instant in whichthe magnets are in close proximity to coils 130. In such position theactual gap between coils 130 and magnets 110 in some embodiments issmaller than 0.2 mm, for example being as small as 0.01 mm. Similar gapsare provided between magnets 110 and endoscope 90 (on the inside ofprotector 100). In some embodiments of the invention coils 130 arearranged not to be diametrically opposite, for example where there is anodd number of coils, for example three coils, at angular intervals of120 degrees. The number of magnets 110 (e.g., 2, 3, 4, 6 or any larger,smaller or intermediate number) is not necessarily equal to the numberof coils 130 (e.g., 2, 3, 4, 6 or any larger, smaller or intermediatenumber).

In some embodiments of the invention, magnets 110 are electromagnetsrather than permanent magnets as in other embodiments. Alternatively tolead based power conduction, in an alternative embodiment of theinvention, disc 102 is powered by an induced electric filed, forexample, using a AC magnetic field generator or an RF field which arereceived by an antennas (not shown) on housing 140, as known in the art.Alternatively, the external power source comprises a rapidly rotatingmagnet, which directly causes disc 102 to rotate.

Alternatively to using an electromagnetic motor, a fluid motor, forexample pneumatic (e.g., using air) or hydraulic (e.g., using salinesolution) may be used. The pressurized fluid, which may be available viaendoscope 90 for performing the procedure, is optionally directed at aplurality of fins attached to disc 102 (corresponding to magnets 110) orat depressions in the circumference of disc 102, thereby causing thedisc to rotate.

Bearings 150 and bearings 160, if of ball or of cylinder type, rotate inthe opposite direction to the rotation of disc 102, thus the gyroscopeeffects of bearings 150 and 160 are in the opposite direction as thegyroscope effect of the rotation of disc 102. In some embodiments, toincrease the offset of the gyroscope effect of rotating disc 102,bearings 150 and/or bearings 160 are designed to increase theirgyroscope effect, for example by manufacturing them of high densitymaterials, by extending the bearings axially, and/or by increasing thenumber of bearings used.

Debris which reaches disc 102 is given a centrifugal acceleration bydisc 102, and reach a rim 1410 (FIG. 5) of housing 140 with aconsiderable velocity. As shown in FIG. 5 below, rim 1410 of housing 140is optionally shaped, e.g., flared, to divert the debris away from theplane of disc 102.

Referring back to FIG. 1, control box 104 optionally includes a switch106. In some embodiments switch 106 has three positions: OFF, ON, andRESTART. In some embodiments of the invention only two positions areprovided: ON and RESTART. In an exemplary embodiment of the invention,once the protector is turned on, the protector can operate only for afixed amount of time, for example, 10 minutes, 1 hour or two hours. Thisforces the use of the protector or the power supply (if detachable) as adisposable unit. In an exemplary embodiment of the invention, a powersupply 108 used for protector 100 comprises a battery. Wear of thebearings in such a short time may be less important, allowing a lowercost device to be produced. In an exemplary embodiment of the invention,the protector is provided in a package along with instructions for useand/or an indication of matching endoscopes.

In an exemplary embodiment of the invention, disc 102 is rotated using alow amount of torque, for example, only sufficient to continue rotation,but not sufficient to overcome any real amount of friction or to restartthe rotation. This provides a safety feature in case disc 102 touches asensitive membrane. In an exemplary embodiment of the invention, theRESTART switch is provided to enable a surge of power to be provided toprotector 100, so that the torque is sufficient to restart rotation.

Alternatively, the restart surge is provided automatically a short timeafter the rotation of disc 102 stops. Alternatively or additionally, aperiodic surge is provided automatically.

FIG. 4 is a schematic view of the moving part 400 of a one-moving-partlens protector, in accordance with an alternative exemplary embodimentof the present invention. Part 400 comprises a substantially transparentdisc 102, a sleeve shaft 410, and a plurality of radially polarizedmagnets, fastened together into one mechanical unit on the inside,outside or integral with sleeve shaft 410, as a magnet unit 420. Shaft410 is optionally in the form of a round hollow tubular cylinder,optionally of thickness 0.05-0.15 millimeter, and is fastened to disc102, optionally by an adhesive. Magnet unit 420 is made of amagnetizeable material, optionally neotron 666 and is fastened to shaft410, optionally by an adhesive and optionally polarized in axial strips.The thickness of magnet unit 420 is in some embodiments in the range 0.2mm-0.8 mm. The diameters and the lengths of shaft 410 and magnet unit420 and their thickness are determined by the diameter of the lens whichthe specific lens protector is designed to protect, for example, between5 mm and 10 mm. In various exemplary embodiments of the invention thelength of shaft 410 ranges from 7 millimeter to 20 millimeter and itsinternal radius ranges between 3 millimeter and 15 millimeter. Invarious exemplary embodiments of the invention the length of magnet unit420 ranges from 5 millimeter to 17 millimeter. It should be noted thatthe design of the coils and the magnets, together with the power levelprovided, determine the torque that can be achieved.

FIG. 5 schematically shows a cross-sectional view of a housing 500 forthe one-moving piece lens protector of FIG. 4, in accordance with anexemplary embodiment of the present invention. Rim 1410 of housing 500is shaped to divert debris, which were given a centrifugal velocity bydisc 102, away from the plane of disc 102. At the opposite side ofhousing 500 is a rim 510 which holds shaft 410 in a fashion enablingrotation and/or engages the body of endoscope 90. Rim 510 optionallyacts as a slider bearing (as bearing 160). Optionally rim 510 is made ofa self-lubricating material for example nylon 66, teflon, delarin,okolon, or a polycarbonate. Coils 130 are provided to supply themagnetic fields which cause the rotation of part 400. In someembodiments coils 130 are embedded in the wall of housing 500.Alternatively, coils 130 are fastened thereto. In an exemplaryembodiment of the invention, coils 130 comprise elongate rectangularcoils. Coils 130 terminate in leads 132, connecting to control box 104(FIG. 1). In some embodiments of the invention, the connections betweencoils 130 are in a triangular configuration. Alternatively, a starconfiguration is used for the connection.

FIG. 6 is a schematic oblique cut-away view of sheath 190 in accordancewith some exemplary embodiments of the present invention. In theembodiment shown, sheath 190 is designed for an endoscope 90. Lensprotector 500 is situated at the inserted end of endoscope 90, oppositethe endoscope eyepiece 94. Leads 132 are optionally embedded in sheath190, by any of the techniques well known to a practitioner of the art,optionally with sheath 190 being constructed using one of the techniquesknown as hollow-tube plastic extrusion.

Endoscope sheath 190 is optionally provided with a pressure balancingmechanism, for example a plurality of holes 192, to prevent a pressuregradient forcing gasses and perhaps carried particles from the inside ofthe patient into lens protector 100 and into sheath 190.

In some embodiments of the invention sheath 190 is fabricated as anintegral part of lens protector 100. In use, endoscope 100 is insertedinto sheath 190 until reaching lens protector 100 and there it connectswith lens protector 100, optionally by screwing into screw threads atthe base of housing 500. Alternatively or additionally, alignment oflens protector 100 is performed with ball and depression arrangementssuch as click-stops.

Alternatively to being used for an endoscope, a similar lens protectormay be constructed to fit a surgical (including ophthalmic) microscope.

A low profile lens protector may also be used for other application,where a high-profile lens protector is not suitable, for example, forfield binoculars, sights and laser range finders. In such embodimentsthe lens protector 100 and it parts will be of the appropriatemeasurements, which may differ considerably from the measurementsmentioned above. Optionally the direction of rotation of the pair oflens protectors for each of the lenses rotates in opposite directions,thus balancing out the gyroscope effect caused by the rotation.

In the description and claims of the present application, each of theverbs, “comprise” “include” and “have”, and conjugates thereof, are usedto indicate that the object or objects of the verb are not necessarily acomplete listing of members, components, elements or parts of thesubject or subjects of the verb.

The present invention has been described using detailed descriptions ofembodiments thereof that are provided by way of example and are notintended to limit the scope of the invention. The described embodimentscomprise different features, not all of which are required in allembodiments of the invention. Some embodiments of the present inventionutilize only some of the features or combinations of features fromdifferent ones of the shown embodiments.

The detailed description is provided by way of example and is not meantto limit the scope of the invention, which is limited only by thefollowing claims:

1. A low profile medical lens protector for a medical viewing devicewith an entrance aperture having a given diameter, comprising: arotatable view-through clement which does not block said entranceaperture; a motor which rotates said view-through element; and a housingenclosing said view-through element and said motor, characterized inthat said housing has an outer diameter less than 10 mm greater thansaid given diameter.
 2. A protector according to claim 1, wherein saidouter diameter is less than 5 mm greater than said given diameter.
 3. Aprotector according to claim 1, wherein said outer diameter is less than2.1 mm greater than said given diameter.
 4. A protector according toclaim 1, wherein said view-through element is integral with a rotor ofsaid motor.
 5. A protector according to claim 1, wherein said housing isintegral with a stator of said motor.
 6. A protector according to claim1, wherein said housing has a flared rim.
 7. A protector according toclaim 1, wherein said motor is a magnetic motor.
 8. A protectoraccording to claim 7, wherein said motor comprises a plurality ofaxially disposed magnets, attached to said view-through element.
 9. Aprotector according to claim 8, comprising at least one tension ringpreventing radial motion of said magnets.
 10. A protector according toclaim 7, wherein said motor comprises a magnetic ring, attached to saidview-through element.
 11. A protector according to claim 1, wherein saidmotor comprises a hollow rotor.
 12. A protector according to claim 11,comprising at least two axially displaced bearings coupling said rotorto said housing.
 13. A protector according to claim 12, wherein said atleast one of said bearings is a slip ring bearing.
 14. A protectoraccording to claim 12, wherein said at least one of said bearings isrotating bearing.
 15. A protector according to claim 12, wherein saidbearings arc at either end of said housing.
 16. A protector according toclaim 1, comprising a power source that provides only enough power tosaid motor to maintain said view-through element in rotation and not toinitiate rotation.
 17. A protector according to claim 16, wherein saidpower source is operative to provide a power surge sufficient toinitiate rotation of said view-through element.
 18. A protectoraccording to claim 1, wherein said viewing device comprises an invasiveviewing tube device.
 19. A protector according to claim 18, wherein saidviewing tube is flexible.
 20. A protector according to claim 18 adaptedto attach to said viewing tube.
 21. A protector according to claim 20,wherein said protector is attached to said tube substantially only at aproximal part of said protector, distal from said view-through element.22. A protector according to claim 20, comprising a sheath adapted tofit on said viewing tube.
 23. A protector according to claim 22, whereinsaid sheath defines at least one axial tube.
 24. A protector accordingto claim 20, comprising a short sleeve for coupling said protector tosaid viewing tube.
 25. A protector according to claim 20, wherein saidprotector is integral with said viewing tube.
 26. A protector accordingto claim 18, wherein said viewing tube comprises at least one workchannel and wherein said protector comprises at least one tube extensionthat can be aligned with said channel.
 27. A protector according toclaim 1, wherein said view-through element rotates at at least 5,000r.p.m.
 28. A protector according to claim 1, wherein said view-throughelement rotates at at least 10,000 r.p.m.
 29. A protector according toclaim 1, wherein said view-through element rotates at at least 20,000r.p.m.
 30. A protector according to claim 1, wherein said protector hasan outer diameter of less than 30 mm.
 31. A protector according to claim1, wherein said protector has an outer diameter of less than 20 mm. 32.A protector according to claim 1, wherein said protector has an outerdiameter of less than 7 mm.
 33. A protector according to claim 1,wherein said view-through element is optically transparent.